"...pointed it furiously under Flint's arm at Malfoy's face. A loud bang echoed around the stadium and a jet of green light shot out of the wrong end of Ron's wand, hitting him in the stomach and sending him reeling backwards on to the grass. 'Ron! Ron! Are you all right?' squealed Hermione. Ron opened his mouth to speak, but no words came out. Instead he gave an almightly belch and several slugs dribbled out of his mouth on to his lap."

The Slug-Vomiting Charm[2] (Slugulus Eructo) is a charm that causes the victim to burp up slugs and slime for approximately ten minutes; they may also take on a sallow complexion as a side-effect. It is described as a green jet of light.

Rupert Grint stated that vomiting slugs was the most challenging scene to film in that movie: "I think coughing up slugs was quite hard. Ron has a scene where he has to cough up these giant slugs. I had this giant slug in my mouth loaded with slime and I spat them out. I think it was plastic. I hope it was plastic."[4]

Despite the challenge, Rupert apparently enjoyed filming the scene: "It was so fun because they had all these different flavours of slug slime. There was chocolate, there was lemon, there was orange, there was peppermint. All these different flavours - they made them taste really nice."[5]